1. Field of the Invention
The present invention relates to a hard sintered body cutting tool, and more specifically, it relates to a hard sintered body cutting tool which is made of cubic boron nitride (CBN) and diamond.
2. Description of the Background Art
Diamond is a hard material which is most excellent in thermal conductivity. In general, therefore, a diamond sintered body which is prepared by sintering diamond particles under a very high pressure is widely applied in cutting tools. Such a diamond sintered body is employed for cutting a nonferrous metal such as an aluminum alloy, in particular. On the other hand, a sintered body of CBN (cubic boron nitride), which is next to diamond in hardness, is mainly employed for cutting a ferrous material.
While a diamond sintered body is widely employed for cutting a nonferrous metal such as an aluminum alloy as described above, wear resistance of such a diamond sintered body is extremely reduced when the same is used for cutting a ferrous material such as cast iron or hardened steel, for example, due to reaction of the diamond particles with iron.
Further, when a CBN sintered body, which is mainly employed for cutting a ferrous material as described above, is used for cutting an aluminum alloy, aluminum is disadvantageously deposited on a rake face of such a CBN sintered body, to cause chipping.
Therefore, if a diamond or CBN sintered body is employed for simultaneously working an aluminum alloy and cast iron, which are materials increasingly applied to automobile components, for example, the life of the sintered body is disadvantageously reduced.